1. Field of the Invention
The present invention generally relates to an occupant sensing apparatus for detecting a seated person on a seat.
2. Description of the Related Art
An example of an occupant sensing apparatus is disclosed in U.S. Pat. No. 5,232,243.
The occupant sensing apparatus includes a piezoelectric film sensor and a controller. The piezoelectric film sensor is disposed in a seat and is oscillated by a driving circuit. The controller is connected to the piezoelectric film sensor and monitors an oscillation value of the piezoelectric film sensor. When a person is seated on the seat, the piezoelectric film sensor contacts a contacting arm of the seat. Therefore, the oscillation value of the piezoelectric film sensor is attenuated. As a result, the controller determines a seated condition of the seat in accordance with the oscillation value of the piezoelectric film sensor.
However, the occupant sensing apparatus needs the driving circuit for oscillating the piezoelectric film sensor. Also, the piezoelectric film sensor is expensive. Therefore, the detecting apparatus becomes complicated and expensive.